The Mosquito Effect: how malarial chaos influenced human history

April 25 has been recognised globally by the World Health Organization (WHO) as World Malaria Day (previously African Malaria Day), since 2006 to highlight the need for continued investment and innovation.

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The “butterfly effect” from chaos theory might result in a Tornado, but the “mosquito effect” (through the parasite it carries) has fundamentally altered human migration patterns, enabling European colonisation and reshaping the geopolitical landscay of entire continents. The mosquito, a seemingly insignificant insect, wielded astonishing power and profoundly altered human civilisation. Malaria, derived from the Italian “mala aria,” meaning “bad air’, is a saga of discovery, colonisation, human suffering and scientific breakthroughs.

Before modern science unravelled malaria’s secrets, people believed it was caused by miasma—poisonous air emanating from marshes. It wasn't until 1880 that the French military doctor Alphonse Laveran observed the malaria parasite from the blood of soldiers who had succumbed to fever in Algeria. However, identifying the parasite was just the first puzzle; the full picture of malaria’s transmission remained elusive. In 1885-86, Camillo Golgi and Angelo Celli demonstrated the cyclical nature of the fever in relation to the parasite. In 1892, Ettore Marchiafava further characterised the five species of the parasite, distinguishing Plasmodium falciparum from others. Of notable mention is Patrick Manson, often regarded as the ‘father of tropical medicine,’ who first established the role of mosquitoes in disease transmission with filariasis and later mentored Ronald Ross. In 1894, Manson hypothesised that mosquitoes could transmit malaria, too. Ross, inspired by Manson’s theory, identified the parasite in the gut of the Anopheles mosquito after studying avian malaria in birds in 1897. His breakthrough paved the way for understanding human disease. Giovanni Battista Grassi made significant contributions by linking human malaria to the female Anopheles mosquito in 1898. By 1898, the complete transmission cycle of malaria was scientifically understood.